Tape core



Dec. 4, 1962 J. D. MULi-u-:RENl ETAL TAPE CORE Filed June 50, 1961 lO 3l I l l I I3 l l l FIG! INVENTORS JOSEPH D. MULH EREN JOSEPH C. GUlNAN YMf ATTORNEY 3,056,794 TAPE EUR@ Joseph D. Miribel-en, Waterviiet, andJoseph C. Guinan, Troy, N.Y., assignors to Norton Company, Troy, NX., acorporation of Massachusetts Filed .lune 30, 196i, Ser. No. 121,147 2Claims. (Cl. 2do- 59) The present invention relates generally to tapesin roll form and more particularly to pressure sensitive adhesive tapesin roll form and to cores for supporting such tapes in such form.

The problem of telescoping or the displacement of the convolutions of atape roll laterally from one side of the core upon which it is wound isone which has been particularly bothersome to the pressure sensitivetape manufacturers.

Several solutions have been suggested including that of U.S. Patent No.2,772,774 to George R. Rabuse wherein a core is provided which supportsthe tape solely at the central portion of its width, leaving the lateraledges unsupported. The present invention constitutes an improvement overcores of the type described in the Rabuse patent.

It is an object of the present invention to provide an improved core foruse in supporting pressure sensitive adhesive tapes wound thereon inrolly form.

Another object of the invention is to provide an improved roll of tapewhich is resistant to telescoping Additional objects, if notspecifically set forth herein will be readily apparent to one skilled inthe art from the following detailed description of the invention:

In the drawings:

FIGURE 1 is a plan view of one type of core embodying the presentinvention.

FIGURE 2 is a cross-sectional view of the core of FIGURE l showing across-section (in dotted lines) of a roll of pressure sensitive tapeWound upon the core.

FIGURE 3 is a plan View of a different embodiment of a core of thepresent invention.

FIGURE 4 is a cross-sectional view of the core of FIG- URE 3 showing across-section (in dotted lines) of a roll of pressure sensitive' tapewound upon the core.

Generally, the present invention is based on the discovery that it isdesirable to wind pressure sensitive tapes upon cores under substantialtension in order to produce hard rolls. This minimizes undesirablegapping and iiuting of the rolls upon aging. However, hard windingpromotes the tendency to telescope Many variations of core constructionhave been tried to permit hard winding without telescoping. Thestructure of the Rabuse cores illustrated in U.S. Patent No. 2,772,774appear to be the closest prior art to the solution arrived at by thepresent inventors-but with one major and important difference. It hasbeen found that supporting the tape by the mid-portion only of a core astaught by Rabuse does not permit sufficiently hard winding of thetape--there being a tendency for the tape to slip to one side or theother during winding. The cores of the present invention support thetape across the entire width thereof and achieve relief from telescopingnot by providing relief areas for the compressive forces Within the rollbut by providing a positive locking of the tape to the core whereby thecompressive forces are balanced and telescoping is minimized.

Specifically, the present invention relates to cores for pressuresensitive adhesive tapes wherein the tape-supporting peripheral surfaceof the core is provided with a plurality of areas of differentelevation-all of which are in contact with the tape wound thereon. Thechange in elevation of the areas provides a positive lock againstdisplacement of the tape and is carried through the su- Bfihjti PatentedDee. 4, i955@ perposed convolutions of tape, providing a slightcurvature of the tape roll in cross-section. This slight curvature hasbeen found sutiicient to prevent compressive forces built up within theroll from causing the convolutions to displace laterally in theundesirable telescoping action.

Referring now to the drawings, the core illustrated in FIGURES 1 and 2provides a dat central portion 11 of the peripheral surface 12 of core18, and a pair of surfaces f3 of different elevation than surface 11.Surfaces 13 are tapered downwardly from the central portion il of core10 at a very slight angle-preferably 1/2". As will be seen from FIGURE2, when a tape strip has been wound convolutely on core 10 to form atape roll i4 (shown in cross-section by the dotted lines), the tape isin intimate contact with the entire peripheral surface I2 of coreitipressing against both surface 11 and surfaces f. This produces acurvature in the tape which is repeated out to the periphery of the rollas shown at 15. A tape roll on such core will be very resistant totelescoping and, since the tape is in hrm contact with the entire widthof the core, can be wound very hard without difficulty in keeping truealignment of the 4edges of the roll.

The core of FIGURES 3 and 4 is `a further variation of the presentinvention. The peripheral surface 22 of core 2G is composed ofalternately disposed wedge shaped surfaces 2l raised above the normalsurface 22 of the peripheral surface of core 2t). The elevation ofsurfaces 21 is critical only in that it must not be great enough topermit the tape wound thereon to bridge the normal surfaces 22 of core20. A distance of 0.0015" has been found desirable in practice. In thepreferred embodiment of this type of core, the wedge-shaped surfaceshave an included angle of 41. The: tape wound upon such core willreproduce the pattern throughout the convolutions as shown at 24 ofFIGURE 4. This locks the tape in roll form positively on the core andminimizes telescoping The present invention is not limited to anyparticular type of pressure sensitive tape but includes both paper andfilm-backed tapes. The cores of the present invention are preferablymade from a suitable plastic but may be of pressed paper or the like ifdesired. Obviously many variations and modifications may be made withoutdeparting from the spirit and scope hereof and hence only suchlimitations are intended as are imposed in the appended claims.

We claim:

l. A roll of pressure sensitive tape comprising: an annular supportingcore having a tape-supporting surface, said surface having a taper fromthe mid-portion thereof towards each edge, said taper being towards theaxis of said core; and a plurality of convolutions of pressure sensitivetape wound under tension about said surface, said first convolution oftape being of substantially the same width as the surface of said coreand entirely in contact with said surface of said core and conforming tothe taper thereof, and the remaining convolutions of tape beingsuperposed over and conforming to said iirst convolution whereby theouter surface of each convolution has a slight convex curvature andtelescopng of the roll is prevented.

2. A roll as in claim l wherein said surface comprises a hat centralsection and tapered areas on each side of said flat section, the degreeof taper not exceeding 1/2.

References Cited in the le of this patent UNITED STATES PATENTS1,769,928 Lindenberg July 8, 1930 1,948,438 Brunet Feb. 20, 19342,772,774 Rabuse Dec. 4, 1956

